WASHINGTON — The Pentagon’s inspector general is launching an investigation as to whether the U.S. Air Force improperly certified SpaceX launch systems, it announced Monday.

“Our objective is to determine whether the U.S. Air Force complied with the Launch Services New Entrant Certification Guide when certifying the launch system design for the Evolved Expendable Launch Vehicle-class SpaceX Falcon 9 and Falcon Heavy launch vehicles,” Michael Roark, deputy inspector general for intelligence and special program assessments, wrote in a memo addressed to Air Force Secretary Heather Wilson.

Exactly what is prompting this review is unclear. The IG’s memo does not specify what, if anything, raised suspicions about the Air Force’s 2015 certification of Falcon 9 and 2018 certification of Falcon Heavy.

An Air Force spokesman referred Defense News to the inspector general’s office for comment.

“This was a self-initiated project by the Office of Inspector General," Dwrena Allen, the spokesperson for the Pentagon’s Office of Inspector General, told Defense News. "It is one of the key projects in the OIG’s expanding oversight focus on the Department of Defense’s space, missile defense, and nuclear management challenges.”

A query to SpaceX was not immediately returned.

The investigation will start this month and take place at Space and Missile Systems Center at Los Angeles Air Force Base, Roark’s memo states.

Bloomberg first reported news of the investigation.

Since becoming certified, SpaceX rockets have transported a number of high-profile national security payloads into space.

A Falcon 9 system boosted the Air Force’s first next-generation GPS satellite into orbit in December. That event also marked the first SpaceX launch under the service’s Evolved Expendable Launch Vehicle program. In 2017, a Falcon 9 launched Boeing’s unmanned X-37 space plane as part of its latest mission.